* Continuous, but limited, Rwandan support to M23 -experts
* Congo army said to collaborate with Rwandan Hutu rebels
* UN-backed regional peace deal signed in February
Military officers from Rwanda and Democratic Republic of Congo are fueling violence in eastern Congo despite pledges by the countries to foster peace, according to a confidential U.N. experts' report seen by Reuters on Friday.
A rebel group in eastern Democratic Republic of Congo continues to recruit fighters in neighboring Rwanda with the aid of sympathetic Rwandan military officers, the U.N. Group of Experts said in its interim report to the Security Council's Congo sanctions committee.
The U.N. Group of Experts also said elements of the Congolese military have cooperated with a Rwandan Hutu rebel group against the Congolese M23 rebel group, a Tutsi-dominated rebellion of former Congolese soldiers that has demanded political concessions from President Joseph Kabila's government.
The allegations are likely to displease Kigali and Kinshasa, which have signed a U.N.-backed peace agreement and pledged to cooperate on bringing peace and stability to mineral-rich eastern Congo, where millions of people have been killed and many more displaced in decades of conflict.
Recruitment and other forms of support for the M23 rebels have waned in recent months, though the insurgent forces still pose a security threat in eastern Congo, said the U.N. Group of Experts.
"Since the outset of its current mandate, the group has to date found no indication of support to the rebels from within Uganda, and has gathered evidence of continuous - but limited - support to M23 from within Rwanda," the report said.
"The group sent a letter to the government of Rwanda on 14 June 2013 asking for clarification about this support and looks forward to a reply," the U.N. experts said in the 43-page report.
They said current and former M23 members reported that Rwandan army officers or their representatives have crossed the border into Chanzu or Rumangabo in eastern Congo to meet with Makenga.
The report said 14 former M23 soldiers told the Group of Experts that Rwandans who deserted M23 and tried to go home to Rwanda were "forcibly returned to M23" by Rwandan army officers.
Rwanda's deputy U.N. ambassador, Olivier Nduhungirehe, rejected the allegations. "Now that the GoE report was leaked, can you name any single RDF officer mentioned as aiding the M23? NONE!" he wrote on his Twitter feed.
Rwanda has previously complained about the experts. In March Kigali refused to issue entry visas to two panel members, describing them as biased, Nduhungirehe told Reuters at the time.
CONGOLESE TROOPS WORK WITH HUTU REBELS
Collaboration between elements of the Rwandan military and M23 continue, it said. "The Group received information that M23 commanders have regularly met with RDF (Rwandan Defense Forces) officers," the report said.
"Three former M23 officers, a former M23 cadre, and several local authorities told the Group that from March through May 2013, they had witnessed M23 Colonels Kaina and Yusuf Mboneza with RDF officers at the border of Kabuhanga," it said.
But it said that since the brief fall of provincial capital Goma in November 2012 the Group of Experts has not received evidence of full Rwandan army units supporting M23. Also, the March surrender of former M23 leader Bosco Ntaganda has hurt the rebels' morale and sparked desertions, it said.
Last year the experts accused Rwanda's defense minister of commanding the M23 rebellion, which it said was being armed by Rwanda and Uganda, both of which sent troops to aid the insurgency.
The latest report said there was no current signs of Ugandan government support for M23 but noted that limited recruitment activities by the M23 continued on Ugandan territory. It added that Ugandan officials have thwarted several attempts at M23 recruitment.
The allegations come as the United Nations, which has a large peacekeeping force known as MONUSCO in the region, prepares to deploy a special intervention brigade in eastern Congo. That brigade's goal is to aggressively search out and destroy armed groups operating in eastern Congo.
M23 has been generating income of around $180,000 a month from taxes - $200 to $1,000 per truck depending on the load - they exact on the population in the areas where they have been active, the report said.
"The Group notes that sanctioned individual Col. Innocent Kaina of M23 remains engaged in the recruitment of children," it said.
The experts said that they have also received information indicating collaboration between the Congolese military and FDLR rebels, the remnants of Hutu killers who carried out the 1994 genocide of Tutsis in Rwanda, in North Kivu.
The Congolese U.N. mission was not immediately available for comment on the report.